A luggage room is formed between a rear seat back of an automobile and a back door thereof. This luggage room is made expandable by tilting forward the rear seat back provided so as to be tiltable forward. Then, a luggage board is provided on a bottom surface of the luggage room.
As heretofore disclosed in Japanese Patent Laid-Open Publication No. 2003-118500, as a luggage board structure, a structure has been known, in which a hinge recessed groove is additionally provided on a spacer board that is attached to a front edge portion of a luggage floor trim and hides a gap between the luggage floor trim and a rear seat, and a spring member is attached to the hinge recessed groove so that a front half portion of the spacer board can sag in up and down directions from the hinge recessed groove taken as a base point, and so that a front side of the spacer board can be always urged in a down direction from the hinge recessed groove taken as such a base, whereby the spacer board is allowed to follow a forward tilting operation of the rear seat back.
However, in such a conventional technology, the hinge recessed groove as a rotation center of the spacer board and a center shaft as a rotation center of the spring member are located at positions different from each other, and accordingly, there is an apprehension that rotations of the spacer board and the spring member may be hindered by a relative positional shift of both thereof, which occurs at the time when both thereof make the rotations.
Therefore, as disclosed in Japanese Patent Laid-Open Publication No. 2006-143037, there has been known one in which a tip end of an arm of the spring member is slidably engaged with an auxiliary board in order to absorb the relative positional shift.
However, in order to slidably engage the tip end of the arm of the spring member with the auxiliary board, it is necessary to elongate a length of the arm of the spring member by an amount that the relative positional shift is absorbed in addition to that a hinge mechanism of the spacer board and the spring member becomes complicated. Accordingly, there is a problem that weight of the structure is increased. In particular, when a rotation angle of the spacer board is increased, the relative positional shift is also increased, and accordingly, such a problem of the weight increase significantly appears in the case where the rotation angle of the spacer board is increased.
In this connection, it is an object of the present invention to obtain a hinge mechanism capable of increasing the rotation angle by means of a lightweight and simple structure, and to obtain an automotive luggage board structure using the hinge mechanism.